Understanding the Balance Sheet - Unrealized Gain?

[bunk3m]

Hi.

I have setup two currencies as I had one client who paid in USD and I'm
using CAD.  I had a USD bank account, USD A/R, USD Income.  The only
expenses in USD were some bank charges.  I did update the USD/CAD
exchange rate monthly when I had bank fees or when I moved $ from USD
Check to CAD Check using the actual currency rate for the transaction.

I notice in the balance sheet that I have an "Unrealized Gain" (never an
"Unrealized Loss").

On every line in the Balance Sheet, I can click and see the transactions
that made up that balance.

How does one go about understanding which transactions created the
"Unrealized Gain"?

Thanks
B.